Soil organic carbon stocks in relation to elevation gradients in volcanic ash soils of Taiwan

Soil organic carbon (SOC) stocks are controlled by factors with varying degrees of importance at different spatial scales. In this study, soil data were collected from recently sampled pedons and previous studies on volcanic origin soils in Yangmingshan (YMS) National Park in northern Taiwan. This study evaluated the effect of soil order, vegetation type and elevation on the SOC stocks of humid subtropical volcanic ash soils. Analysis results indicate that SOC stock (mean±standard deviation) was 15.6±4.5kgm−2m−1 (n=40) for Andisols and 17.3±7.3kgm−2m−1 (n=20) for Inceptisols with andic soil properties. Meanwhile, SOC stocks under silver grass (17.4±5.5kgm−2m−1, n=20) and bamboo (17.9±2.5kgm−2m−1, n=8) were significantly higher than those under secondary forests (14.9±6.0kgm−2m−1, n=32). Additionally, statistically significant linear regressions were found between the mean SOC stock and the mean of elevation classes. Climate, vegetation types and soil mineralogy vary along elevation gradients in the complex terrain. Our results demonstrated that elevation is a simple and effective predictor of SOC stock. •Humid and warm weather conditions led to lower SOC stocks in volcanic ash soils.•SOC stocks under different vegetation types were mainly controlled by elevation.•Elevation is a simple and effective factor to predict SOC stocks.